The invention relates to a stand-up bag of a heat-sealable or weldable plastic film for containing in particular flowable or pourable products and comprising:
two opposing side walls sealed together along lateral edges thereof by means of side seams;
an inwardly folded bottom wall extending between the lower portions of the side walls and sealed to the respective side walls along transverse bottom seams and along bottom side seams; and
an inwardly folded top wall extending between the upper portions of the side walls and connected to the respective side walls along transverse top connections and sealed to the respective side walls along top seams.
Stand-up bags of this type are known inter alia from U.S. Pat. No. 3,935,993 and DE-A-2553853. Due their excellent standing properties and stability the bags have been used for a wide range of products, in particular for liquid, paste-like, powdery and granular products. It is however considered a drawback of the known stand-up bags that they are difficult to open why a pair of scissors or a knife is often needed orxe2x80x94as for instance known from WO 93/16928 and EP-A-2.0380.110xe2x80x94they are provided with special discharging arrangements for easy removal of the product which makes the bag more expensive.
The object of the invention is to provide a stand-up bag of the above type which is easy to open toollessly and which is simple and inexpensive to manufacture.
The stand-up bag according to the invention is characterised in that one side wall comprises a first side wall section and a second side wall section overlapping the first side wall section in a transverse overlapping area between transverse edges of the two side wall sections, that the side wall sections in the overlapping area are connected by means of longitudinal peelable connections along the side seams and by means of a transverse peelable connection, and that the second side wall section extends beyond the transverse peelable connection to form a gripping member. The bag is thus easy to open by gripping and pulling the gripping member, whereby the transverse peelable connection and the longitudinal peelable connections are broken.
According to the invention the bottom seam between the said one side wall and the bottom wall may be provided between the latter and the first side wall section extending from the bottom seam towards the top connection such that its transverse edge is positioned adjacent said top connection, and that the top connection between the said one side wall and the top wall is provided between the latter and the second side wall section situated outermost in the overlapping area. By providing the edge of the first side wall section close to or immediately adjacent the top seam, it is optimised that the packed product remains in the interior of the bag when the bag is opened.
Moreover according to the invention the top connection between the said one side wall and the top wall may be provided between the latter and the first side wall section extending from the top connection a distance downwards towards the bottom seam, and that the bottom seam between said one side wall and the bottom wall may be provided between the latter and the second side wall section situated outermost in the overlapping area and extending from the bottom seam upwards towards the top connection such that the transverse edge thereof is situated adjacent said top connection.
Furthermore according to the invention the gripping member of the second side wall section may be provided with two interspaced incisions in the free edge thereof. It is thereby possible to provide the bag with apertures of several different sizes. When gripping the gripping member between the two incisions, an aperture is formed having a width substantially corresponding to the distance between the incisions, the second side wall section or the flap section being torn along lines extending from the two incisions. By gripping the gripping member in the portion between one of the incisions and the adjacent side seam, an aperture is formed having a width substantially corresponding to the distance between the said incision and the longitudinal peelable connection along the said side seam. It is also possible to form an aperture of a width corresponding to the distance between the two side seams by gripping the gripping member above the two incisions.
Furthermore according to the invention the first side wall section may have an outer sealing medium layer which heat-seals peelably to the inner sealing medium layer of the second side wall section.
In the above embodiment of the invention, the outer sealing medium layer of the first side wall section may be a copolymer comprising polyethylene and polypropylene when the inner sealing medium layer of the bag walls is made from substantially polyethylene. As a result the stand-up bag may be made from a single film web comprising an inner sealing medium layer of substantially polyethylene and an outer sealing medium layer which is a copolymer comprising polyethylene and polypropylene.
In the second last-mentioned embodiment of the invention the outer sealing medium layer of the first side wall section may comprise polypropylene modified to provide a peelable heat seal to polypropylene when the inner sealing medium layer of the bag walls is made from substantially polypropylene. As a result the stand-up bag may be made from a single film web having an inner sealing medium layer substantially being polypropylene and an outer sealing medium layer comprising modified polypropylene to provide a peelable heat seal to polypropylene.
Moreover according to the invention the peelable connections in the overlapping area of the side wall sections may comprise a peelable strip of the hot-melt type applied to at least one of the two mutually facing surfaces of the side wall sections in the overlapping area thereof. Such a hot-melt strip is easy to apply and provides the peelable connections with a peel strength which is easy to control.
Furthermore according to the invention the peelable connections may comprise a film strip arranged in the overlapping area of the two side wall sections and firmly (non-peelably) heat-sealed to one of the two side wall sections, preferably the second side wall section, the strip having a first surface of a sealing medium corresponding substantially to the sealing medium of the adjacent side wall section and heat-sealed peelably to the other side wall section, preferably the first side wall section, the strip having a second surface of a sealing medium heat-sealed peelably to the sealing medium of the adjacent side wall. This embodiment of the invention makes it possible to use plastic films with the same outer and inner sealing medium. When the sealing medium is substantially polyethylene, the first sealing medium surface of the strip is also made from polyethylene, while the second sealing medium surface thereof advantageously may be a copolymer comprising polyethylene and polypropylene. When a plastic film with an outer and an inner sealing medium layers of polypropylene is used for the bag walls, the first surface of the strips is correspondingly made from polypropylene and the other surface thereof is made from modified polypropylene to provide a peelable heat seal to polypropylene.
Moreover according to the invention the peelable connections may comprise a film strip arranged between the two side wall sections in the overlapping area and having a first and a second outer sealing medium layer with which the film strip is firmly (non-peelably) heat-sealed to the respective side wall sections, said film strip further comprising an intermediate layer peelably connected to at least one of the outer sealing medium layers having a tear resistance weaker than the peel strength between the intermediate layer and the said sealing medium layer. The peelable connection is thus opened by tearing the weak sealing medium layer on both sides of the sealing seam and by a delamination between the weak sealing medium layer and the intermediate layer. This embodiment of the invention makes it possible to use plastic films with the same outer and inner sealing medium, whichxe2x80x94as mentioned abovexe2x80x94may be made from substantially polypropylene or polyethylene. The sealing medium layer of the film strip is also made substantially from polypropylene or polyethylene.
The above embodiment further makes it possible to provide the bag with a degree of reclosability when a pressure-sensitive adhesive, eg. an adhesive of the hot-melt type, is used as the intermediate layer. As the intermediate layerxe2x80x94as mentioned abovexe2x80x94is exposed when opening the peelable connections of the bag and the intermediate layer is of a self-sealing adhesive, after the initial opening of the bag said layer is able to adhere to the surface of the opposed side wall section.
Finally according to the invention the peel strength of the peelable connections may be in range from 100 to 800 g/20 mm, preferably from 200 to 600 g/20 mm, and most preferably from 300 to 500 g/20 mm.